Method of making cutting tools



Feb. 27, 1945. o. c. MARTIN METHOD OF MAKING CUTTING TOOLS OriginalFiled April 20, 1940 PIIIrI 0775 6'. RT/A9 INVEN Patented Feb. 27, 1945zuuirno :sTArEs enzram pence "METHOD .OF MAKING CUTTING TOOLSOtisfiCiMartim Los Angeles, Calif.

Original application LAP! ."20, 1940, Serial No. 5330;752. Dividedand'this;application March I6,1942,"Serial No. 434,812

:3 Claims.

Myinvention-relates to a method of making boring andforming tools'andhas particular re'ference-tea method'of making a .boring .tool which is"particularly adapted to the manufacture "of 'fiuidcontrol valve bodies.

This applicationis a division of my copending application Serial'No.330,'752,'filed April 20,1940,

and entitled'Method and apparatus for manufacturing valve bodies.

In my copending application Serial'Nof323g3'76, filed March 11, 1940,entit1ed"Va1ve, I have described and claimeda novel'fiuid valveconstruction which is particularly adapted "for usein air craft for'controlling various. types of'iflui'd power apparatus. The particularlynotable advantages inherent. in this new valvereside in.its.small size,light weight, and inexpensive construction. The present inventionisdirected to certainitoolsiby means of which this new valve may bereadily and inexpensively constructed.

'Valves of the character disclosed in my aforementioned copendingapplicationSer-ial'N03312:),- 3'76 employ a plurality of bores and.chambers, .a part of whichare used to house valve members and a part ofwhich constitute fluid entrance and exit openings. These .bores andchambers are provided .with various enlargements which function as"fluid passages, andcertain of.these are disposed. in intersectingrelation withenlargements of adjacent bores to provideai'fiuidjintercommunication between .bores. .Priorto my .inventionthesebores and .enlargementsihad to.be formed by destructiblecoresemployed inconnection withthe casting ofcast valvebodiesoniin the caseof valves requiringa valvebody. of greater strength and higher qualitythan .could i be ,obtained .by casting, by .means .of .boring tools.requiring theuse of a. separate tool foreaohbore and. enlargementthereof. and "frequently. required a separate and distinct setup.of..the boring machine .for each operation. Such methodsofmanufacture are expensive and time consuming.

It is therefore an object cf vmy inventionto provide a method ofmanufacturinga boring tool which is particularly adapted tense inthemanufaoture of valves of the character setfforth hereinhefore.

'It is also an'object of myinventionto provide a'method of makingaboring tool comprising "a tool shank and a laterally extending cuttingelement whereby thecross'sectional'shape ofthe shank isso proportionedwith'respect'to the diameter of the bore-enlargement to=be formed 'bythe tool as to'provide a maximum possible-amount of material in theshank.

It is another object of my invention to provide a method of thecharacter set forth in the preceding paragraph of ,making a tool wherebythere'is impartedto the shank .portionofthe tool a lenticular. crosssection.

fit is an additional object of my invention to provide a;method of thecharacter. set forth in the; preceding paragraph or manufacturing atoolwhereby "there is'in parted .to the shank portion of *the:too1alenticular cross sectional shapedefined. by eccentrica'lly disposedcylindrical surfaces, .eachhaving'aradius of curvature substantiallyequal'to "the radius of the pilot bore inwhich the toolis torbe used. I

*Other*objectsaridtadvantages of my inventioirwill .beflp arentfrom "astudy of the 'followmg "specificationspreau'in connection with theaccompanying dr awing wherein:

"Fig.11-isai'fra'gmentary sectional view illustrat ingthe manner'in'which a boring tool constructed "in-accordance with the method of myinvention may be employed for providing enlargementsinthepi'lot'boresformed' in a valve body;

Fig. 2 is "a"crosssectional View illustrating the manner inwhich"to0ls"0f,thecharacter-shown in Figil' arereceived'intheir"respective bores prior to'the "commencement" of a boring operation;

-Fig53 is'a view similar toFig. 2"but il1ustrating'thapo'sition ofthetools at the conclusion of theboringoperation :and

i?ig.--i--is -a'crcss"sectional-view of the shank of a boringtoolconstructed in accordance with the method'of-myinventionrandillustrating the location of the principal "axes employed in theformingpperaticnwhereby the particular shape illustratediinthe drawingis impartedto the tool.

Phave illustrated in .theaccompanying drawing the use "of tthe tool of'my invention as directedto theformingnf a valve body of the characterusedin a va-lve such as that disclosed and claimed in my-copend-ingapplication Serial No. 323376, "filed liiarch '11, '1940,entitled Valve. The *valve'wh-ich-is disclosed in that applicationemploys -avalve body I (see .Fig. 1) Within" which is provided adischarge I port '3 and a'valvwchamberbore5. The discharge'bore 3is'provide'd at its lower :end with an enlargement semen intersects asimilarly disposed enlargement '1 formedin the valve chamberbore. 5.

The enlargements "1 and *8 which "are to be for-med at thelower'endsof'the'bores'a and -5 may be cenveniently bored-by means of a boring toolsuch as that illustrated in the drawing. "Thistool-preferablycompiises-a bar portion H5 adapted to'rbe -carriedin thetool carriage of a suitable boring machine or "engine lathe. The "bar [4bears omits-outermost end' a'shankportion l5 which terminates ina-cutterportionl6.

The-*bloclg l is mounted forrotation about the axis of the bore to beenlarged (such as the bore 3 in Fig. l) as by clamping the block Isecurely to the face plate or in a chuck of an engine lathe. The barortion i4 is suitably mounted on the tool carriage of the lathe and thecarriage is moved to such position as to insert the tool within the bore3 to the desired depth. The block I is then rotated and the tool ismoved laterally relative to the axis of rotation of the block I so as tobring the cutter portion [6 thereof into engagement with the walls ofthe bore and remove the material therefrom to provide the enlargement 8.

According to the preferred embodiment of my invention, the cutterportion [6 and the shank portion i5 are formed integrally with eachother and integrally with the bar portion M as illustrated in Fig. 1. Inaccordance with the preferred method of manufacturing the tool, a barportion M of any desired size is first turned as by means of a lathe toa cylinder having a diameter slightly smaller than the diameter of thebore 3 or 5 in which the tool is to be used, as is indicated by thedotted line I! in Fig. 4, and having a length somewhat in excess of thedepth of the bore 3 or 5. This cylindrical portion may be formed in alathe by rotating the bar I4 about its longitudinal axis indicated byreference character is in Fig. 4. The shank portion I5 is then formed bycutting away the material from one side of the cylindrical portion IT.This may be done by mounting the cylinder I! for rotation in a latheabout an axis such as that indicated at 19 in Fig. 4 and cutting thematerial by means of a lathe tool along a surface 2!] whichisconcentrically disposed relative to the axis 19 and which has a radiusof curvature equal to the radius of the cylindrical portion I1.

Since it is desired to retain a maximum amount of material to serve asthe shank portion I5 in order that the strength thereof may bemaintained at a maximum, the offset between the axes l8 and I9 is soadjusted as to permit the surface 20 to be brought into contact with thesides of the bore 3 or 5 at the time the tip of the cutter l6 hasreached itsmaximum lateral penetration to form the enlargement l or 8.The offset between the axes i8 and I 9 will be found to be equal toone-half the difference in diameter between the bore in which the toolis to be inserted and the diameter of the enlargement to be cut therein.For example, if it is desired to cut a one inch diameter enlargement ina diameter bore, the offset between the axes l8 and I9 will be T31; ofan inch or one-half of the difierence between one inch and of an inch.

I have indicated by means of a dotted circle 2| in Fig. 4 the maximumpermissible diameter which could be employed on the shank if that shankwere formed of cylindrical cross section. It will be observed that asubstantial increase in the amount of material retained in the shank I5is achieved by forming the shank with a lenticular cross section asabove described, and attention is further directed to thefact that thelong axis of this cross section is extended in the direction to bestwithstand the forces imposed thereon by the engagement of the cutter I6.with the block I. After the shank I5 is formed, the upper part of thecircular member remaining at the outermost end thereof is cut away alonga line 2m to provide an upper tool race having the proper rake to givewhatever cutting angle is desired at the cutting edge zlb of the cutterportion l6. Similarly, the underside of the cutter portion 16ispreferably relieved along a surface 210 to provide for the requiredclearance between the flank of the tool and the work.

I have illustrated in Fig. 2 the relation of the cutter i6 and the shankIS with the bore 3 or 5 at the time the cutter is inserted in the borepreparatory to cutting the enlargement I or 8. I have also illustratedin Fig. 3 the relationship between these parts at the time the cuttingof the recess I or 8 is completed.

It will be apparent from the foregoing that I have provided a novelboring tool and method oi making the same which provides a maximumamount of material in the shank portion of the tool interconnecting thecutter with the supporting bar portion and that this shank material isdisposed in such configuration as to achieve the maximum strength andrigidity.

.While I have in the foregoing described as a use to which the tool ofmy invention is particularly adapted, the manufacture of a particulartype of valve such as that disclosed in my aforementioned copendingapplication, it will be readily apparent to those skilled in the artthat the tool is also well adapted to the manufacture of valve bodies ofvarious types and in fact to the forming of bores having enlargementsand recesses in metal parts of various descriptions.

While I. have shown and describedtthe preferred embodiment of myinvention, I do not desire to be limited to any of the details ofconstruction shown or described herein, except as defined in theappended claims.

I claim:

1. The method of making a boring tool for cutting in a valve body anenlargement of a pilot bore provided therein which consists in turningon an end portion of a piece of tool stock a cylindrical section havinga diameter substantially equal to the diameter of said pilot bore,forming a tool shank portion of lenticular cross section by rotatingsaid cylindrical section about an axis disposed parallel to the axis ofsaid cylindrical section and spaced therefrom a distance substantiallyequal to the difierence between the radii of said pilot bore and saidenlargement and cutting a partially cylindrical surface thereon spacedfrom the end thereof and having a radius of curvature substantiallyequal to the radius of said pilot bore, and then cutting away the upperpart of the end portion remaining to form an upper tool faceintersecting said cylindrical section to define a cutting edge.

2. The method of forming a shank on a boring-tool intended for cuttingan enlargement in a pilot bore which consists in cutting away a stockmember along partially cylindrical surfaces each having a radius ofcurvature substantially equal to the radius of said pilot bore andhaving axes spaced apart a distance substantially equal to thedifference between the radii of said pilot bore and said enlargement.

3. The method of forming a shank on a boring tool intended for cuttingan enlargement in a pilot bore which consists in successively rotating astock member about parallelly disposed axes spaced apart a distancesubstantially equal to the diiference between the radii of said pilotbore and said enlargement, and in each instance cutting away a part ofsaid stock member by moving a cutting tool along a path parallel to saidaxis and spaced therefrom a distance substantially equal to the radiusof said pilot bore.

OTIS C. MARTIN.

